Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02416379 2003-O1-16
TITLE:
Self foamable Organoclay/Novolak Nanocomposites
and Process thereof
FIELD OF THE INVENTION
The present invention relates to self foamable and cross-linkable
Organoclay/Novolak
i0 nanocomposites having a novolak resin component and a layered silicate
component,
linked to each other through a covalent bond. More particularly it relates to
compositions and foams derived from such nanocornposites. The present
invention
also encompasses a process for producing the self foamable and cross-linkable
nanocomposite material, as well as the process for producing the nanocomposite
foam.
BACKGROUND OF THE INVENTION
Phenolic foams are recognized as versatile foam compositions, which may be
used in
a variety of materials, such as thermal insulator, fresh flower support, and
building
2o materials. Usually phenolic foams are based on resole-type resin which are
expanded
using chemical blowing agents. For example, conventional novolak-type phenolic
foams described in French Patent application published under No. 2,502,161 and
U.S.
Patent No. 4,698,370, are produced using chemical blowing agents, which may
produce gas during composition curing at high temperature. Chemical blowing
agents
are expensive and some of them are even harmful to humans. Furthermore, a low
compressive and flexural strength limit their use in constructional materials,
which
usually requires high mechanical properties and heat and flame resistance.
Various attempts have been made, to improve the compressive and flexural
strengths
of conventional novolak-type phenolic foams. For example, mixing novolak resin
with an inorganic material, such as calcium carbonate, mica, perlite,
vermiculite,
obsidian, or the like was tried. Unfortunately, the incorporation of such
inorganic
materials results in a brittle composite material because of the very poor
bond strength
between the inorganic material and the novoiak resin. Also, the addition of a
large
volume of inorganic material drastically reduces foaming and curing rates.
2
CA 02416379 2003-O1-16
It would be advantageous to have an alternative Organoclay/Novolak
nanocomposite
and process to make it (for example by polymerisation compounding). It would
also
be advantageous to have foams made from these nanocomposibe and the process
related thereof. More particularly, it would be advantageous to have a process
of
producing such foams which is greatly simplified by the use of water as the
foam
blowing agent. Disadvantages of using chemical blowing agents could therefore
be
avoided. In addition to the novolak-type resin and the layered-silicate, the
nanocomposite compositions disclosed herein may comprise a surfactant and a
curing
agent. The resulting foams generated herein show high mechanical properties
and
to high curing and foaming rates.
The content of each publication, patent and patent aplication mentioned in the
present
application is incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention relates to self foamable and cross-linkable
OrganoclaylNovolak
nanocomposites, compositions, foams produced from these nanocomposites and
process thereof. The nanocomposites and foams disclosed herein may comprise,
for
2o example, a layered silicate component and a novolak resin component that
may be
covalently linked (either directly or through an intermediate). Nanocomposite
or
foam composition may also further comprise a surfactant and a curing agent.
Processes of producing foams disclosed herein exploits water as a blowing
agent. The
blowing agent may be produced in situ during the generation of the
Organoclay/Novolak nanocomposite from raw material (monomers; phenols and
aldehydes). When the Organoclay/Novolak nanocomposite is produced from
oligomer (novolak resin), water may originate from the volatile content of a
novolak
resin itself.
3o It is therefore provided, in a first aspect, a self foamable and cross-
linkable
nanocomposite (foam) material, which comprises:
a) a novolak type phenolic resin having a number-average molecular weight
of 250 to 600 and having a volatile content of 1 to 10R6 (by weight; wt);
b) a layered silicate uniformly dispersed in said resin, said layered silicate
having a layer thickness of about 7 to 12 t~ and an interlayer distance of
3
CA 02416379 2003-O1-16
at least about 4~, wherein said cnsin is connected to said layered silicate
through an intermediate there between;
c) a surfactant;
d) a curing agent; and
e) a produced in situ blowing agent.
In accordance with the present invention, the blowing agent may be produced
(in situ)
during the synthesis of the novolak resin, the blowing agent is preferably
water.
1o In accordance with the present invention, the number-average molecular
weight of the
novolak resin may preferably bt between 350 to 550.
Also in accordance with the present invention, the intermediate may be a
covalent
bond.
Further in accordance with the present invention the layered silicate may be,
for
example, a smectic clay selected from the group consisting of montmorillonite,
nontronite, beidellite, volkonskoite, laponite, hectorite, saponite,
sauconite, nnagadite,
kenyaite, stevensite, vermiculite and mixtures thereof.
In accordance with the present invention, the content of said layered silicate
may be
between 0.05 to 60 parts by weight per 100 parts by weight of the novolak
resin.
Also in accordance with the present invention, the layered silicate may be
reactive
(activated) and intercalated by the condensation reaction of the hydroxyl
group of
layered silicate with monomers or oiigomers having bifuncdonal groups. The
monomers or oligomers may be, for example, toluene diisocyanate, bisphenol A,
hydroquinone and /or phenol-diol.
3o Further in accordance with the present invention, the nanocomposite may be
obtained
by reacting phenolic monomers in situ with layered silicate modified by a
molecule
having bifunctional groups.
Also in accordance with the present invention the monomers may be phenol
(i.e.,
3s phenolic compound) (e.g., phenol, cresol, xylenol, resorcinol, hydroquinone
and the
like) and aldehyde (pare-formaldehyde, acetaldehyde, furfural, and the like).
4
CA 02416379 2003-O1-16
In accordance with the present invention, the nanocomposite may be obtained by
reacting the layered silicate modified by a molecule having bifunctional
groups with
novolak oligomer.
Further in accordance with the present invention, the volatile content in the
novolak
resin may preferably be water. The volatile content in the novolak resin may
preferably be between 2 to 7q6 (by weight).
to In a further aspect, the present invention provides a process for preparing
a self-
foamable and cross-linkable nanocomposite material involves (comprising) the
following steps:
(i) preparing a reactive (activated) and intercalate layered silicate
(organoclay);
(ii) preparing an Organoclay/Novolak nanocomposite
(iii) mixing Organoclay/Novolak nanocomposite with surfactant; and
(iv) mixing OrganoclaylNovolak nanocomposite with a curing agent to form
powdered particles.
2o In accordance with the present invention, step (i) may be conducted in a
reactor.
In accordance with the present invention, step (ii) may be conducted by:
compounding
polymerization of organoclay with novolak resin monomers and oligomers and
surfactant to form the Organoclay/Novolak nanocomposite.
Also in accordance with the present invention, step (ii) may be conducted by:
melt
mixing the organoclay, surfactant and novolak resin through a compounding
extruckr
to form the Organoelay/Novolak nanocomposite.
3o Further in accordance with the present invention step (ii) may be conducted
by:
adding organoclay into the reacting system of novolak-type phenolic resin
before
scatting the reaction, and then melt mixing the mixture with the surfactant in
a reactor
or through a compounding extruder to form novolak-orgsnocaly composite.
Also in accordance with the present invention, step (ii) may be conducted by:
s
CA 02416379 2003-O1-16
-melt mixing the surfactant and novolak resin in a reactor, and then cooling
down, and
-dry mixing organoclay and the mixture of surfactant and novolak resin
through the miller to form the Organoclay/Novolak (nano)composite
Step (ii) may also lx conducted by:
-melt nvxing the surfactant and novolak resin in a reactor, and then cooling
down, and
-melt mixing organoclay and the mixture of surfactant and novolak resin
1o through a compounding extruder to form the Organoclay/Novolak
(nanoxomposite.
In accordance with the present invention, step (iii) may be conducted by dry
mixing
Organoclay/Novolak nanocomposite with a curing agent using a miller to form
powdered particles.
Also in accordance with the present invention, step (iii) may be conducted by
melt
mixing Organoclay/Novolak nanocomposite with a curing agent through a
compounding extruder, and then pulverizing it into powdered paficles using a
miller.
Further in accordance with the present invention, the process for preparing
novolak
type phenolic nanocomposite foam may comprise heating self foamable and cross-
linkable nanocomposite powdered particles at 100 to 250 °C using a hot
press or a hot
furnace.
In an additional aspect, the present invention provides a composition for the
manufacture of a self foamable and cross-linkable Organoclay/Novolak
nanocomposite, comprising:
a) a novolak resin (i.e., novolak-type phenolic resin), and
3o b) a layered silicate,
wherein said resin is covalently linked to said layered silicate thmugh an
intermediate
(linker).
In accordance with the present invention the novolak resin may have, for
example, a
number-average molecular weight of between 250 to 600, preferably between 350
to
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CA 02416379 2003-O1-16
550. Further in accordance with the present invention the novolak resin may
have, for
example, a volatile content of between 1 to 10°k (by weight).
Also in accordance with the present invention, the layered silicate may have,
for
example, a layer thickness of between 7 to 12 t~. Further in accordance with
the
present invention the layered silicate may have, for example, an interlayer
distance of
at least 4 ~.
In accordance with the present invention the composition may further comprise
a
1o surfactant, such as, for example a non-ionic surfactant. The surfactant may
be
selected, for example, from the group consisting of non-ionic siloxane-
oxyalkylene,
oxyalkylated castor oil (castor oiUpolyoxyalkylene copolymer) and
polyoxyalkylated
alkyl phenols and mixture thereof. In the above defined nanocomposite, the
surfactant
may be present in a range of between 0.05 to 20 parts by weight per 100 parts
by
weight of said novolak resin.
In accordance with the present invention, the composition may further comprise
a
curing agent, for example, hexamethylenetetramine or other curing agent. In
the
above defined composition, the curing agent may be present in a range of
between 5
2o to 20 parts by weight per 100 parts by weight of said novolak resin.
Also in accordance with the present invention, the volatile content of the
novolak
resin may preferably be water.
Further in accordance with the present invention, the intermediate (linker)
may be a
covalent bond or it may be a molecule (having bifunctional groups) of formula;
X-P-
Y, wherein P is an organic structure and X and Y are independently selected
fmm the
group consisting of reactive groups such as -0H, -NCO, -Cl, -NH2, etc. For
example,
the linker may be selected from the group consisting of resorcinol, bisphenol
A,
3o hydroquinone, toluene diisocyanate, thionyl chloride (C120S), adipoyl
chloride,
hexamethylenediamine, etc.
In the above defined composition, the layered silicate may be present in a
range of
between 0.05 to 60 parts by weight per 100 parts by weight of said novolak
resin.
7
CA 02416379 2003-O1-16
In a further aspect, the present invention relates to a composition for the
manufacture
of (making) a foam comprising:
a) a novolak resin (i.e., novolak-type phenolic resin);
b) a layered silicate; and
c) a surfactant;
wherein said resin is covalently linked to said layered silicate through an
intermediate
(linker).
In yet a further aspect, the present invention relates to a composition for
the
to manufacture of a foam comprising ;
a) a self foamable and cross-linkable Organoclay/Novolak
nanocomposite having a layered silicate component and a novolak
resin component, and
b) s surfactant;
wherein said layered silicate component and said novolak resin component are
covalently linked through an intermediate (linker)
In accordance with the present invention, the compositions for the manufacture
of a
foam may further comprise a curing agent.
In accordance with the present invention, the nanocomposite may have, for
example, a
volatile content of between 1 to 1090 (by weight).
In accordance with the present invention, the foams defined above may
comprise, for
example, a layered silicate present in a range of between O.OS to 60 parts by
weight
per 100 parts by weight of said novolak resin, and a surfactant present in a
range of
between 0.05 to 20 parts by weight per 100 parts by weight of said novolak
resin.
Also in accordance with the present invention, the curing agent may be present
in a
range of between 5 to 20 parts by weight per 100 parts by weight of said
novolak resin.
3o The surfactant and curing agent may be those defined herein.
In an additional aspect, the present invention relates to a process for
producing an
(self foamable and cross-linkable) Organoclay/Novolak nanocomposite comprising
the step of covalently linking a layered silicate with a novolak resin.
Suitable novolak
resin and layered silicate may be as defined herein.
s
CA 02416379 2003-O1-16
In accordance with the present invention, the step of covalently linking may
be
performed by polymerisation compounding. The step of covalently linking may be
performed by reacting a functional group on said novolak resin with the
activated
surface of said layered silicate. The step of covalently linking may also be
performed
by reacting a linker having a bifunctional group with the activated surface of
said
layered silicate and with a novolak resin, said linker being of formula X-P-Y,
wherein
P is an organic molecule, and X and Y are independently selected from the
group
consisting of -0H, -NCO, -CI, -NH2, etc. The linker may be selected, for
example,
from the group consisting of resorcinol, bisphenol A, hydroquinone, toluene
to diisocyanate, thionyl chloride (CIzOS), adipoyl chloride,
hexamethylenediamine.
Further in accordance with the present invention, the silicate may be selected
from the
group consisting of smectic clay (montmorillonite, nonironite, beidellite,
laponite,
hectorite, saponite, sauconite, magadite, kenyaite, stevensite, and the like),
vermiculite, halloysite, or sericite; or a swellable mica-based mineral, such
as
fluoromica or the tike.
In another aspect, the present invention relates to a process for producing an
(self-
foamable and cross-linkable) Organoclay/Novolak nanocomposite comprising
2o reacting (mixing) an activated layered silicate (e.g., a layered silicate
modified by an
intermediate (a molecule having bifunctional groups as defined herein)) with a
phenolic compound and an aldehyde. The layered silicate may be as defined
herein.
In accordance with the present invention, the nanocomposite may have, for
example, a
volatile content of between 1 to 1096 (by weight). The volatile content may
prefera-
bly be water.
In accordance with the present invention, the phenolic compound may be
selected, for
example, from the group consisting of phenol, cresol, xylenol, resorcinol,
hydroquino-
ne, and the like, and phenols modified with aniline, urea, melamine, or cashew
and the
like.
Also in accordance with the present invention, the aldehyde may be selected
from the
group consisting of formalin, pare-formaldehyde, acetaldehyde, furfural, and
the like.
9
CA 02416379 2003-O1-16
The process, in accordance with the present invention, may further comprise
adding
an acid catalyst.
It is to be understood herein that mixing may occur in successive step, such
as for
example, the addition of an aldehyde (such as formaldehyde) may be performed
by
adding it by drop while stirring (mixing). An acid catalyst may be added, for
example,
before the aldehyde.
to In yet another aspect, the present invention provides a process for
producing a foam
comprising (melt) mixing (i.e., comprising a mixing step);
a) a novolak resin (i.e., novolak-type phenolic resin)
b) a layered silicate;
c) a surfactant; and
d) a curing agent.
It is to be understood herein that the process may be stopped at this step and
the
resulting mix may be shipped or stored (at a suitable temperature). The
process may
be completed later by for example, heating the mixture at a desired
temperature.
In accordance with the present invention, the resin may be covalently linked
to said
layered silicate through an intermediate (linker) as described herein.
Also in accordance with the present invention, the volatile content of the
novolak
resin is mainly water.
The process, in accordance with the present invention, may further comprise
pulverizing the above defined mixture.
3o The process, also in accordance with the present invention, may further
comprise
heating the mixture at a temperature of between 100 and 250 °C (using a
hot press or a
funnace)(and pressing it into a mold). Heating may promote the evaporation of
water
contained in the novolak resin and produced from the condensation of the
phenolic
CA 02416379 2003-O1-16
compound and the aldehyde. Water, upon evaporation may then act as a blowing
agent. Excess water may be removed by distillation under vacuum.
In accordance with the present invention, the surfactant may be selected from
the
group consisting of non-ionic siloxane-oxyalkylene, oxyalkylated castor oil
and
polyoxyalkylated alkyl phenols and mixture thereof.
Also in accordance with the present invention, the curing agent may be, for
example,
hexamethylenetetramine, etc.
to
In an additional aspect, the present invention relates to a process for
producing a
(Organoclay/Novolak nanocomposite} foam comprising;
(melt) mixing (i.e., comprising a mixing step);
a) an OrganoclaylNovolak nanocornposite having a layered silicate component
and a novolak resin component ;
b) a surfactant; and
c) a curing agent.
In accordance with the present invention, the layered silicate component and
the
2o novolak component may be covalently linked through an intermediate (i.e., a
covalent
bond or a linker).
Also in accordance with the present invention, the Organoclay/Novolak
nanocompo
site may have a volatile content of between 1 and 1096 (by weight). The
volatile con
tent of the novolak resin may be water.
In accordance with the present invention, water may be used herein as a
blowing
agent.
3o The process, according to the present invention, may further comprise
pulverizing
the above defined mixture.
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'I9ie process, also in accordance with the present invention, may further
comprise
heating the mixture at a temperature of between 100 and 250 °C (using a
hot press or a
furnace) (and pressing it into a mold).
In another aspect, the present invention relates to a composition including a
nanocomposite comprising a novolak resin covalently attached to a silicate
material.
In accordance with the present invention, the nanocomposite may further
comprise a
surfactant, such as those defined herein. It may also further comprise a
curing agent,
as defined herein.
In accordance with the present invention, the nanocomposite may further
comprise
water as a blowing agent.
In a further aspect, the present invention provides a method for producing a
foam
from an Organoclay/Novolak nanocomposite having a layered silicate component
covalently linked (directly or through a linker) to a novolak resin component,
said
method comprising using water as a blowing agent.
In another aspect, the present invention provides a foam made from a self-
foamable
and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate
component and a novolak resin component, said foam having a compression
strenght
at break (room temperature, 0.1 in/min speed) of at least 15 NiPa.
In accordance with the present invention, the nanocomposite may have a
silicate
component of 5 ~ (by weight). Also in accordance with the present invention,
the
silicate component may be montmorillonite.
In yet another aspect, the present invention provides a foam made frora a self
foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered
silicate component and a novolak resin component, said foam having a
compression
strenght at break (room temperature, 0.1 in/min speed) of at least 40 MPa.
12
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In accordance with the present invention, the nanocomposite may have a
silicate
component of 10 °k (by weight). Also in accordance with the present
invention, the
silicate component may be montmorillonite.
Also in accordance with the present invention the foam made from a self-
foamable
and cross-linkable OrganoclaylNovolak nanoeomposite may have a water
absorption
(room temperature, 36 h) of less than lOqfo (weight).
A "volatile content" as used herein relates to the content of a composition
that
to generates a gas (vapor) upon heating.
In the process of this invention, the foam composition may be incorporated
with a
variety of flame retardants, such as halogen compounds (e.g.,
tetrabromobisphenol A,
hexabromobenzene, Dechlorane, and chlorinated paraffin), phosphorus compounds
(e.
g., triphenyl phosphate and cresyldiphenyl phosphate) and boron compounds (e.
g.,
borax and boric acid).
It is to be understood herein, that an "Organoclay/Novolak nanocomposite foam"
may
be distinguished from the "OrganoclaylNovolak nanocomposite" at the physical
level.
2o For example, it is to be understood herein that the "Organoclay/Novolak
nanocomposite" is the (non-expended) material used to produce the foam. The
foam
is expended by the blowing agent (water produced in situ), and thus comprises
cavities (empty cells), dispersed throughout the foam.
It is to be understood herein, that if a "range" or "group" of substances or
the like is
mentioned with respect to a particular characteristic (e.g. temperature,
pressure, time
and the like) of the present invention, it relates to and explicitly
incorporates herein
each and every specific member and combination of sub-ranges or sub-groups
therein
whatsoever. Thus, any specified range or group is to be understood as a
shorthand
3o way of referring to each and every member of a range or group individually
as well as
each and every possible sub-ranges or sub-groups encompassed therein; and
similarly
with respect to any sub-ranges or sub-groups therein.
- with respect to a temperature of at least 100 °C, this is to be
un~rstood as
specifically incorporating herein each and every individual temperature
state, as well as sub-range, comprising 100 °C and above 100 °C,
such as
13
CA 02416379 2003-O1-16
for example 101 °C,105 °C and up,115 °C and up, 102
°C to 150 °C, up to
210 °C, and 600 °C etc.;
- with respect to a compression strenght at break of at least 15 NlPa this is
to
be understood as specifically incorporating herein each and every
individual compression strenght, as well as sub-range, comprising 15 MPa
and above, such as for example, 15.5 MPa, 20 MPa, 18 MPa, etc.
io BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1A is a graph illustrating the mechanical properties (storage modulus)
of
Novolak foam (pure Novolak) or the Organoclay/Novolak nanocomposite foams of
the present invention; non-grafted nanocomposite foam (MMT-Na-Novolak (5 % wt)
1s and grafted nanocomposites foam (MM'T-TDI-BA-Novolak (596 wt) and MMT-
Phenol-Novolak (5°lo wt)).
Figure 1B is a graph illustrating the mechanical properties (storage modulus)
of
Novolak foam (pure Novolak) or the Organoclay/Novolak nanocomposite foams of
20 the present invention; non-grafted nanocomposite foam (NilVIT-Na-Novolak
(1096 wt)
and grafted nanocompositea foam (MMT-TDI-BA-Novolak (10~o wt) and MMT-
Phenol-Novolak (1096 wt)).
Figure 2A is a graph illustrating a thermogravimetric analysis of Novolak foam
(pure
25 Novolak) and OrganoclaylNovolak nanocomposite foams of the present
invention.
Figure 2B is a graph illustrating the thermal stability of Novolak foam (pure
Novolak)
and Organoclay/Novolak nanocomposite foams of the present invention.
30 Figure 3A is a graph illustrating the X-ray diffraction (XRD) spectra of
MMT
(unmodified) and MMT modified by phenol {MMT-phenol) or TDI-BA (MMT-TDI-
BA).
Figure 3B is a graph illustrating the XRD spectra of Organoclay/Novolak
35 nanocomposite foams of the present invention with 5 % wt montmorillonite
obtained
by compounding or by mixing; Na-MMT/Novolak (compounding, 596 wt), Na-
Z4
CA 02416379 2003-O1-16
Bisphenol/Novolak (compounding, 596 wt), Na-TDI-BA/Novolak (compounding, Solo
wt), Na-TDI-BA/Novolak (mixing, 596 wt).
Figure 3C is a graph illustrating the XRD spectra of OrganoclaylNovolak
nanocomposite foams of the present invention with 10 % wt montmorillonite
obtained
by compounding or by mixing; Na-MMT/Novolak (compounding, 1096 wt), Na-
Bisphenol/Novolak (compounding, 10% wt), Na-TDI-BAlNovolak (compounding,
10% wt).
to DETAILED DESCRIPTION OF THE INVENTION
The phenolic resin used in this invention is a powdered, novolak phenolic
resin that is
prepared by crushing the thermoplastic condensation product formed by reacting
one
or more kinds of phenol with one or more kinds of aldehyde in the presence of
an acid
catalyst. Usually, it is cured with a hardener, such as hexamethylenetetramine
(referred to as H1VITA hereinafter).
Phenol (i.e., phenolic compound) used as a raw material for the phenolic resin
includes, for example, phenol, cresol, xylenol, resorcinol, hydroquinone, and
the like.
2o It may also include those phenols modified with aniline, urea, melamine, or
cashew.
The aldehyde that may be used in the generation of the phenolic resin may
include,
for example, formalin, para-formaldehyde, acetaldehyde, furfural, and the
like. The
acid catalyst may include, for example, sulfuric acid, hydrochloric acid,
phosphoric
acid, and other inorganic acids; and formic acid, oxalic acid, acetic acid, p-
toluene
sulfonic acid, and other organic acids.
The powdered novolak phenolic resin used herein may be, for example, a novolak
resin with a number-average molecular weight of about 250 to 600 or preferably
350
to 550. With a number-average molecular weight lower than 250, the phenolic
resin
3o may be liable to cake during storage and undergo hardening and foaming
reactions,
which are undesirable for uniform foams. With a number-average molecular
weight in
excess of 600, the phenolic resin may be slow in hardening and foaming
reactions and
does not form a foam with a high expansion ratio. It is to be understood
herein that
although the use of novolak resin number-average molecular weight lower than
250 or
higher than 600 may have some undesirable effects, in some circumstances, such
material may prove to be useful.
CA 02416379 2003-O1-16
The volatile content of the novolak resin used herein is present in the range
of 1 to
10% (by weight) or preferably present in the range of 2 to 796 (by weight).
The
volatile content might be measured according to ASTM D-4639. The volatile
content
of the novolak resin includes water and free phenol. In the present invention,
water is
used as a blowing agent and free phenol may find utility in the control the
foaming
rate. The amount of volatile content may vary to suit the desired final
density of the
phenolic foam.
to During the foaming of the novolak-type phenolic nanocomposite, a surfactant
is
present in the chemical composition. Non-ionic siloxane-oxyalkylene,
oxyalkylated
castor oil and polyoxyalkylated alkyl phenols have been used successfully as
surfactants both individually and in combination. For the chemical
composition,
which is the basis of the invention, it is preferable to employ between 0.05
and 20%
surfactant (by weight), preferably present in the range of 2 to 1096 by
weight.
A feature of the invention is that the inorganic fillers used herein are
layered silicates,
which are uniformly dispersed in the phenolic foam. The layered silicate
imparts
advantageous mechanical characteristics and heat and flame resistance to the
phenolic
foam.
A typical layered clay (or layered silicate) suitable for use herein may be a
swellable
clay material, either natural or synthetic, such as, for example, smectic
clay,
vermiculite, halloysite, or sericite; or a swellable mica-based mineral, such
as
fluoromica. Examples of suitable smectic clays are montmorillonite,
nontronite,
beidellite, laponite, hectorite, saponite, sauconite, magadite, kenyaite,
stevensite, and
the like. These layered clays may generally comprise particles containing a
plurality
of silicate platelets. They may be, for example, present in the range of 0.8
to 1.2 nm
thick, may be tightly bound together with an interlayer spacing of, for
example, 0.4
3o nm or less and may contain exchangeable cations (e.g., Na+, Ca+i, K+ or
Mg+Z, etc) at
the interlayer surfaces. It is to be understood herein that the thickness and
interlayer
spacing is not to be restricted to the above mentioned values. In some
circumstances
it might be useful to use layered silicate with greater or lower values of
thickness and
interlayer spacing.
16
CA 02416379 2003-O1-16
The layered clay may be used directly in phenolic foam without any treatment.
However, it may be advantageous to use a layered clay that is modified by an
organic
molecule. Such modification (intercalation) may improve the interfacial
strength
between the silicate layer and the phenolic matrix.
The layered clay (i.e., layered silicate) may be intercalated (modified), for
example,
with an organic molecule (e.g., a swelling agent) capable of undergoing ion-
exchange
reactions with the cations present at the interlayer surfaces of the silicate
layers.
Suitable swelling agents include cationic surfactants such as ammonium
(primary,
to secondary, tertiary and quaternary), phosphonium or sulfonium derivatives
of
aliphatic, aromatic or arylaliphatic amines, phosphines and sulfides. Such
suitable
swelling agents and processes for intercalating layered silicates are
disclosed in U.S.
Patent No. 4,472,538, 4,810,734, 4,889,885 as well as international patent
application
publication No. W092/02582, the complete disclosures of which are incorporated
t5 herein by reference.
However, in the present application, a novel, intercalating approach is used
for
intercalating a layered silicate. This new approach is based on the
condensation
reaction of an organic molecule containing reactive groups (having
bifunctional group,
2o such as hydroxyl groups) with the interlayer surface of the layered
silicate and
subsequently with Novolak resin. The above mentioned organic molecule may be
characterized by the following formula:
X-P-Y
in which P stands for an organic structure, X and Y are reactive groups, such
as -0H,
25 -NCO, -Cl, -NH2 and so on. Organic molecule of such formula include, for
example,
hydroquinone, resorcinol, bisphenol A (BA), linear novolak with a molecular
weight
of 250 to 600, toluene diisocyanate (1'DI), thionyl chloride, adipoyl
chloride,
hexamethylenediamine, and the like.
3o The process of intercalating organic molecules into layered silicates,
therefore
producing an Organoclay/Novolak nanocomposite, may be carried out by a one or
two
steps reaction with or without catalyst.
A typical one step reaction may be, for example;
35 -reacting the layered silicate with hydroquinone, resorcinol, bisphenol A
or
any suitable organic molecule of the above mentioned structure. The reaction
t7
CA 02416379 2003-O1-16
may be performed, for example, using acetonitrile, toluene or cyclohexane as
the solvent and with oxalic acid or hydrochloride as the catalyst.
A typical two-step reactions may be, for example;
-reacting the layered silicate with TDI or thionyl chloride, and;
-reacting the above with BA, HIVJ~A, novolak or hexamethylenediamine.
According to the present invention, the Organoclay/Novolak may be generated by
either producing the Novolak-type resin in situ (by condensation reaction of
the
to phenolic compound and the aldehyde as described above) during the
intercalation
process of the layered silicate or may be produced from novolak resin prepared
in a
separate process and then intercalated with the layered silicate.
Turning now to the preparation of the foam itself. The general steps involved
in the
is preparation of the self foamable novolak-type resin foam from the
nanocomposite
described above may be, for example;
a) mixing the Organoclay/Novolak nanocomposite with a surfactant; and;
b) mixing the above with a curing agent to form powdered particles.
2o More particularly, the surfactant may be added into the novolak resin (by
melt mixing
in a reactor or through a compounding extruder) before its reaction (linking
to) with
the (modified) layered silicate or may be added to the Organoclay/Novolak
nanocomposite after its synthesis.
25 The organoclay may be added together with the surfactant into novolak resin
by melt
mixing in a reactor or through a compounding extruder. The formed
Organoclay/Novolak nanocomposite material containing surfactant may then be
mixed with a certain amount of curing agent by miller to form a powdered
particle.
3o The Organoclay/Novolak nanocomposite foam thus obtained is poured into a
mold of
prescribed shape. The mold is heated to between 100 and 250°C for 2 to
60 minutes
for curing and foaming, using a heating furnace or hot press. In this way
phenolic
resin nanocomposite foam is obtained With a heating temperature lower than
100°C,
the reaction rate of curing and foaming of the phenolic resin nanocomposite
foam
35 material is low and the resulting foam is poor in compressive strength.
With a heating
18
CA 02416379 2003-O1-16
temperature higher than 250 °C, the curing and foaming take place at
such a high rate
that the foam with compact cell structures is not obtained.
The process of this invention produces Organoclay/Novolak nanocomposite foam
better in comparison with conventional foams. A small percentage of layered
silicate
can greatly improve the mechanical properties and it does not decrease the
curing and
foaming rates. It is suitable for the industrial production of phenolic resin
nanocomposites foam.
to The present invention will be further explained by the following non-
limiting and
comparative examples.
Production of Novolak resin 1
A 90% phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a
three-neck flask
equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid
(1.52 g) is
loaded into the phenol melt. A 3796 solution of formaldehyde (102.2 g,
1.26mo1) is
added by drops while stirring at 100 °C. ABer the addition by drops is
complete, the
reaction mixture is refluxed for 2 hours. A fraction of the water generated
during the
2o process is then removed by distillation under atmospheric conditions and at
vacuum
for 1 hour. The obtained product is poured on the aluminum paper. The Novolak
resin
1 comprises water present in the range of 1 to 1096 (by weight) as required
for the
subsequent generation of a foam from the self-foamable and cross-linkable
Organoclay/Novolak nanocomposite.
Production of Novolak resin 2
A 9096 phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a
three-neck flask
equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid
(1.62 g) is
loaded into the phenol melt. A 3796 solution of formaldehyde (80.3 g, 0.99mo1)
is
added by drops while stirring at 100 °C. After the addition by drops is
complete, the
reaction mixture is refluxed for 2 hours. A fraction of the water generated
during the
process is then removed by distillation under atmospheric conditions until 105
ml
water is distilled out. The obtained product is poured onto the aluminum
paper. The
Novolak resin 2 comprises water present in the range of 1 to 10%n (by weight)
as
required for the subsequent generation of a foam from the self foamable and
cross-
linkable Organoclay/Novolak nanocopomsite.
19
CA 02416379 2003-O1-16
Production of Novolak resin 3
A 90% phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a
three-neck flask
equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid
(1.b2 g) is
loaded into the phenol melt. A 37% solution of formaldehyde ( 124.1 g,
1.53mo1) is
added by drops while stirring at 100 °C. After the addition by drops is
complete, the
reaction mixture is refluxed for 2 hours. A fraction of the water generated
during the
process is then removed by distillation under atmospheric conditions until 145
ml
water is distilled out. The obtained product is poured onto the aluminum
paper. The
i0 Novolak resin 3 comprises water present in the range of 1 to 10% (by
weight) as
required for the subsequent generation of a foam from the self-foamable and
cross-
linkable Organoclay/Novolak nanocomposite.
Production of MMT-TDI-BA
Two grams of Na-montmorillonite (Na-MMT), 0.9 g of toluene diisocyanate (TDI),
0.004 g of DBTDL (dibutyltin dilaurate) and acetonitrile (50 ml) were
introduced into
a glass reactor. The mixture was stirred for 6 hours at 60°C. Then, 1.6
g of BA was
added into the mixture and the reaction was carned out for 2 hours. The
obtained
2o product was washed by acetonitrile in order to remove free TDI and BA
monomers.
The product is named MMT-TDI-BA.
Production of MMT-Phenol
Two grams of Na-montmorillonite (Na-MMT), 0.9 g of hydroquinone and 0.04 g of
oxalic acid were introduced into a glass reactor containing 50 ml of
acetonitrile. The
reaction was conducted for 6 h at 80 °C under stirring. The final
product was washed
by acetonitrile or acetone up to no free hydroquinone monomer. The product is
named
MMT-phenol.
PRODUCTION OF NANOCOMPOSITES BY POLYMERIZATION COMPOUNDING
EXAMPLE 1: Production of MMT-Na-Novolak Nanocomposite 5 wt%
Three grams of Na-MMT, 56.4 g of phenol and 0.54 g of oxalic acid were
introduced
into a glass reactor. The mixture was stirred and heated at 100 °C and
after 1 hour
3b.5 ml of formaldehyde was added. The reaction was carried out while being
stirred
for 2 h 30 min. 32 ml of water were removed by distillation under vacuum.
CA 02416379 2003-O1-16
Nanocomposites thus produced comprise, water in an amount sufficient for the
subsequent generation of a foam from the self foamable and cross-linkable
Organoclay/Novolak nanocomposite.
EXAMPLE 2: Production of MMT-Na-Novolak Nanoaomposite 10 wt~o
Six grams of Na-MMT, 56.4 g of phenol and 0.54 g of oxalic acid were
introduced
into a glass reactor. The mixture was stirred and heated at 100°C and
after 1 hour 36.5
ml of formaldehyde was added. The reaction was carried out while being stirred
for 2
to h. 32 ml of water were removed by distillation under vacuum. Nanocomposites
thus
produced, comprise water in an amount sufficient for the subsequent generation
of a
foam from the self foamable and cross-linkable OrganocIay/Novolak
nanocoraposite.
EXAMPLE 3: Production of MMT-TDI-BA-Novolak Nanocomposite 5 wt96
Three grams of MlViT-TDI-BA, 56.4 g of phenol and 0.54 g of oxalic acid were
introduced into a glass reactor. The mixture was stirred and heated at
100°C and after
1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while
being
stirred for 2 h. 32 ml of water were removed by distillation under vacuum. The
2o nanocom~osites, thus produced comprise water in an amount sufficient for
the
subsequent generation of generation of a foam from the self foamable and cross-
linkable organoclay/novolak nanocomposite.
EXAMPLE 4: Production of MMT-TDI-BA-Novolak Nanooompoalte 10 wt9b
Six grams of MMT-TDI-BA, 56.4 g of phenol and 0.54 g of oxalic acid were
introduced into a glass reactor. The mixture was stirred and heated at
100°C and after
1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while
being
stirred for 2 hours. 32 ml of water were removed by distillation under vacuum.
3o Nanocomposites thus produced, comprise water in an amount sufficient for
the
subsequcnt generation of a foam from the self foamable and cross-linkable
Organoclay/Novolak nanocomposite.
EXAMPLE 5: Production of MMT-Phenol-Novolak Nanocomposlte 5 wtR6
Three grams of MMT-TDI-BA, Sb.4 g of phenol and 0.54 g of oxalic acid were
introduced into a glass reactor. The mixture was stirred and heated at
100°C and after
21
CA 02416379 2003-O1-16
1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while
being
stirred for 2 hours. 32 ml of water were removed by distillation under
vacutun.
Nanocomposites thus produced, comprise water in an amount sufficient for the
subsequent generation of a foam from the self foamable and cross-linkable
Organoclay/Novolak nanocomposite.
EXAMPLE 6: Production of MMT-Phenol-Novolak Naaocomposite 10 wt96
Six grams of MMT-phenol, 56.4 g of phenol and 0.54 g of oxalic acid were
to introduced into a glass reactor. The mixture was stirred and heated at
100°C and after
1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while
being
stirred for 2 hours. 32 ml of water were removed by distillation under vacuum.
Nanocomposites thus produced, comprise water in an amount (quantity)
sufficient for
the subsequent generation of a foam from the self foamable and cross-linkable
i5 Organoclay/Novolak nanocomposite.
EXAMPLE 7: Production of MMT-TDI-BA-Novolsk Nanocomposite
Two grams of Na-montmorillonite (Na-MMT), 0.98 of toluene diisocyanate (TDn
2o and 0.0048 of DBTDL were put into a glass reactor containing 50 ml of
acetonitrile.
The reaction was then conducted for 6 h at 60 °C while being stirred
followed by
adding 2.48 of linear novolak (from example 3; Novolak resin 3) into the
reaction
mixture and reacting for 2 hours. The obtained product was washed by
acetonitrile or
acetone until no free TDI monomers and novolak polymers remained. The product
is
25 named MMT-TDI-BA-Novolak 1. Nanocomposites thus produced, comprise water
in an amount sufficient for the subsequent generation of a foam from the self
foamable and cross-linkable Organoelay/Novolak nanocomposite.
3o EXAMPLE 8: Production of MMT-TDI-BA-Novolak Nanocomposite
A MMT-TDI-BA (7.5g), 9096 phenol liquid (1888, l.8mo1 phenol) was heated to
100°C in a three-neck flask equipped with a reflex condenser, stirrer,
and dropping
funnel. Oxalic acid (1.628) was loaded into the phenol melt. A 3796 solution
of
formaldehyde (102.28, 1.26mo1) was added by drops while being stirred at
100°C.
35 After the addition by drops was complete, the reaction mixture was refluxed
for 2
hours. After cooling down to 80°C, Sg Surfonic CO-42 was added into the
mixture
and stirred for 5 min. Some water was then removed by distillation. The
obtained
22
CA 02416379 2003-O1-16
product was poured onto the alumintun paper and named MMT-TDI~BA-Novolak 2.
Nanocomposites thus produced, comprises water in an amount sufficient for the
subsequent generation of a foam from the self foamable and cross-linkable
Organoclay/Novolak nanocomposite.
PRODUCTION OF NOVOIAK NANOCOMPOSITES FOAM
Nanocomposites obtained by polymerfxation compounding
EXAMPLE 9:
The nanocornposites prepared by polymerization compounding were mixed with
lOwt9b of a curing agent, like hexamethylenetetramine (1~1~ITA), and pulverize
into
powder. The powder was put into a mold and pressed to foam, for around 5
minutes at
~5 130 °C. It was heated to 165-170 °C for 10-15 minutes. During
all the presses, the
pressure was kept at 5 psi. Then the mold was cooled down and the novolak
nanocomposite foam was removed.
Nanocomposite obtained by mixing
EXAMPLE 10:
Then grams of novolak resin (production of novolak example 1), 0.5 g Na-MMT
TDI-HA-Novolak 2 and 0.5 g Surfonic CO-42 ane put into a flask and heated to
95 'C,
mixed for 5 minutes and cooled. The mixture was mixed with 1.1 g HMTA and
pulverized into powder. The powdered Organoclay/Novolak nanocomposite material
is poured into a 12 x 12 x 5 mm mold, The mold is installed on a hot press at
130 °C
for 5 min and heated to 175 °C and kept 10 min at 175 'C. Then the mold
is cooled
down and the novolak nanocomposite foam is removed.
EXAMPLE 11:
Eleven grams of novolak nanocomposite material (production of novolak resin
2), are
added to 1.1 g HMTA and the mixture is pulverized into powder. The powdered
novolak nanocomposite material is poured into a 12 x 12 x 5 mm mold and the
mold
is installed on a hot press at 130 'C for 5 minutes and heated to 175
°C. The
temperature is kept at 175 'C for 10 min. The mold is cooled and 8te novolak
nanocomposite foam is removed.
23
CA 02416379 2003-O1-16
EXAMPLE 12:
Ten grams of novolak resin (production of novolak resin 1) are added to 0.5 g
Na-
MMT (no any modification) and O.Sg Surfonic CO-42 into a flask, heated to 95
°C,
mixed 5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and
pulverized
into powder. The powdered novolak nanocomposite material is poured into a 12 x
12
x 5 mm mold, the mold is installed on a hot press at 130 'C for 5 min and
heated to
175 °C. The temperateure is kept at 175 °C for 10 minutes. The
mold is cooled and the
novolak nanocomposite foam is removed.
to EXAMPLE 13:
Ten grams of novolak resin (production of novolak resin 2) are added to 0.5 g
MMT-
TDI-BA-Novolak Z and O.Sg Surfonic CO-42 into a flask, heated to 95 °C,
mixed for
5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and pulverized into
powder. The powdered novolak nanocomposite material is poured into a 12 x 12 x
5
mm mold, the mold is installed on a hot press at 130 'C for 5 minutes and
heated to
175 °C. The temperature is kept at 175 °C for 10 minutes. The
mold is cooled and the
novolak nanocomposite foam is removed.
EXAMPLE 14:
2o Ten grams of novolak resin (production of novolak resin 3) are added to 0.5
g MMT-
TDI-BA-Novolak 2 and 0.5g Surfonic CO-42 into a flask, heated to 95 °C,
mixed for
5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and pulverized into
powder. The powdered novolak nanocomposite material is poured into a 12 x 12 x
5
mm mold, the mold is installed on a hot press at 130 'C for 5 minutes and
heated to
175 °C. The temperature is kept at 175 °C for 10 minutes. The
mold is cooled and the
novolak nanocomposite foam is removed.
Results presented in Table 1 and 2 indicate that the foam generated from the
self
foamable and cross-linkable Organoclay/Novolak nanocomposite and prepared by
3o polymerization compounding have good mechanical properties in comparison
with
conventional phenolic foam nanocomposites. The compressive strengths at break
are
two times greater for our products (MMT-TDI-BA-Novolak (5°J6 wt)) and
there is
also no break over 44.6 KN for the self foamable and cross-linkable
nanocomposite
foam at 10~o wt of MMT; for the conventional nanocomposite at l0fo wt of MMT
the
break is obtained at 21.8 KN. The nanocomposites present a lower water
adsorption.
The storage modulus of the nanocomposite foam of the present invention which
are
24
CA 02416379 2003-O1-16
prepared by polymerization compounding is higher than that of conventional
nanocomposite foam.
s TABLE 1: Compression strength: room temperature, 0.1 ln/min speed.
samples Compression strength at break
(MPa)
Pure Novolak ?.2
MMT-Na-Novolak (5% wt) 11.9
MMT-TDI-BA-Novolak (Slo 21.3
wt)
MMT-Phenol-Novolak (5% wt) 16.7
MMT-Na-Novolak (10k wt) 21.8
MMT-TDI-BA-Novolak (1096 Over 43.5 KN load no break
wt)
MMT-Phenol-Novolak (1096 Over 44.6 KN load no break
wt)
CA 02416379 2003-O1-16
TABLE 2; Water Absorption (room tarnperature, 36 hours)
Samples Weight Weight Absorption
(beforo {after absorption)(96)
absorption)
Pure Novolak 5.6269 5.9695 6.1
MMT-Na-Novolak (596 8.6192 8.9003 3.3
wt)
MMT-TDI-BA-Novolak 7.70709 7.4345 5.1
(56 wt)
MMT-Phenol-Novolak 8.b132 8.9398 3.8
(56 wt)
MMT-Na-Novolak ( 1096 - - -
wt)
MMT-TDI BA-Novolak 9.6313 10.3502 7.5
(10~o wt)
MMT-Phenol-Novolak 8.8748 9.4371 6.3
(106 wt)
26
